JP3069707B2 - Wireless coordinate reader for detecting height information - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate reading device for inputting coordinates to an external device such as a computer, and more particularly, connects a coordinate reading device body and a coordinate indicator with a signal line. The present invention relates to a wireless coordinate reading device that does not need to be performed.

[Summary of the Invention] The present invention relates to an excitation line laid on a sense line plate,
When a coordinate indicator having a resonance circuit composed of a coil and a capacitor is placed on the sense line plate, wireless coordinates for obtaining coordinate values from an induction signal induced on the sense line by electromagnetic coupling between the excitation line, the coil, and the sense line It is an object of the present invention to realize a coordinate reading device capable of detecting height information of a position where a coordinate indicator is placed in a reading device.

For this purpose, in the present invention, a metal reading plate is provided below the sense line plate, and height information detecting means for calculating height information based on frequency information of a guide signal guided to the sense line is provided to constitute a coordinate reading device. did.

As the coil incorporated in the coordinate indicator moves away from the metal plate placed under the sense line plate, the inductance of the coil changes and the induced signal frequency information changes, so that it is converted to height information. -ing

[Prior Art] Techniques for obtaining height information in a coordinate reading device include:
A technique using the amplitude of an induction signal is known. FIG. 8 is an explanatory diagram thereof. Excitation line 102 and sense line 1
03 is arranged orthogonally to form a sense line plate 101, an alternating current signal is applied to the excitation line 102, and the induction signal induced on the sense line 103 is observed and converted to height information. -ing

[Prior Art] Techniques for obtaining height information in a coordinate reading device include:
A technique using the amplitude of an induction signal is known. FIG. 8 is an explanatory diagram thereof. Excitation line 102 and sense line 1
03 are arranged orthogonally to form a sense line plate 101, an AC signal is applied to the excitation line 102, and an induced signal induced on the sense line 103 is observed. Coordinate indicator 104 is coil 1
Built-in resonance circuit with 05 and capacitor.

When the coordinate indicator 104 is placed on the sense line plate 101 as shown in the figure, an induction signal is generated on the sense line 103 by the electromagnetic coupling of the excitation line 102, the coil 105, and the sense line 103. If the coordinate indicator 104 is directly above the sense line plate 101, the amplitude of the induction signal increases, and the sense line plate
The amplitude decreases as the distance from 101 decreases. If the induction signal is amplified and detected and the amplitude is measured, the height information of the coordinate indicator can be obtained.

[Problems to be Solved by the Invention] The above description describes the principle. Actually, a plurality of excitation lines 102 and a plurality of sense lines 103 are provided as a sense line plate 101, and a coordinate indicator 104 is provided as a sense line. The plate 101 is placed at an arbitrary position on the plane. It is not placed at a fixed point as shown in FIG.

For this reason, in the technique using the amplitude of the guidance signal as the height information, the amplitude changes depending on the position on the plane where the coordinate indicator is placed, and the height information cannot be detected accurately. there were.

For example, on the straight line x shown in FIG.
As shown in FIG. 9, the amplitude of the induction signal becomes maximum at the center of the sense line 103 and decreases as it moves to the periphery as shown in FIG.

The present invention has been made to solve the above problems in the conventional technology. The main object is a wireless coordinate reading device that does not require a signal line to connect between the coordinate reading device main body and the coordinate pointing device, and can also detect height information of a position where the coordinate pointing device is placed. It is an object of the present invention to realize a wireless coordinate reading apparatus, and more specifically, to realize a wireless coordinate reading apparatus capable of detecting height information with high accuracy without being affected by a position.

[Means for Solving the Problems] In order to solve the above problems, a feature of the first configuration of the wireless coordinate reading device according to the present invention is to induce an excitation line for generating an AC magnetic field based on an excitation signal and an induction signal. A sense line plate on which a sense line is arranged, and a coordinate indicator electromagnetically coupled to the sense line plate,
In a wireless coordinate reading device for obtaining a coordinate value of a position where the coordinate indicator is placed based on the guidance signal, a metal plate is provided below the sense line plate, and based on frequency information of the guidance signal, the guidance indicator is It is characterized in that height information detecting means for obtaining height information of a position placed on the sense line plate is provided.

In the wireless coordinate reading device according to the first configuration, the height information detection unit receives the excitation signal and the induction signal, detects a phase of the induction signal, and outputs a phase signal as a phase signal; A wireless coordinate reading device according to the second configuration can be configured by providing a control device that inputs the phase signal and converts the coordinate signal into height information of a position where the coordinate indicator is placed on the sense line plate. .
Further, in the wireless coordinate reading device according to the first or second configuration, the coordinate indicator has a resonance circuit including a coil and a capacitor, and thus the wireless coordinate reading device can be configured. Still further, in the wireless coordinate reading device having the above-described configuration, a plurality of excitation line groups and a plurality of sense line groups are arranged in a superposed manner to constitute a sense line plate, and an AC signal is sequentially applied to the excitation line groups. , The sense line group is sequentially selected, and a coordinate value of a position where the coordinate indicator is placed is obtained from a guidance signal guided to the sense line, whereby a wireless coordinate reading apparatus can be configured.

[Operation] According to the coordinate reading device based on the first configuration, when an alternating magnetic field is generated from the excitation line and the coordinate indicator is placed near the excitation line and the sense line, the induction signal is transmitted to the sense line. Occurs.

On the other hand, the inductance of the coil incorporated in the coordinate indicator changes depending on the distance between the coil and the metal plate disposed below the sense line plate. This change in inductance changes the resonance frequency of the resonance circuit formed by the coil,
This is a factor that changes the frequency information of the induction signal. The height information detecting means detects the frequency information of the induction signal guided to the sense line and converts the frequency information into height information.

Embodiment (Configuration of Coordinate Reading Apparatus According to First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1 to FIG.

First, the configuration will be described. 1, 2, and 3 show the configuration of a coordinate reading apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a sense line plate on which an excitation line group 2 and a sense line group 3 are laid. The excitation line group 2 and the sense line group 3 form a folded loop,
They are arranged at equal intervals. In the first embodiment, the excitation line group 2 and the sense line group 3 are arranged orthogonally.

Although not shown in FIG. 1, a metal plate 13 is disposed below the sense line plate 1 with a spacer 14 interposed therebetween, as shown in the sectional view of the sense line plate in FIG.

Reference numeral 4 denotes an excitation scanning circuit to which each excitation line of the excitation line group 2 is connected. The excitation scanning circuit 4 is composed of a plurality of electronic switch elements such as analog switches, and supplies an excitation signal ds supplied from an excitation circuit 6 described later to one selected excitation line. Reference numeral 5 denotes a sense scanning circuit to which each sense line of the sense line group 3 is connected. Like the excitation scanning circuit 4, it is configured by an electronic switch element, and one of the sense lines is selected and connected to an amplification detection circuit 7 and a phase detection circuit 8 described later. 6 is an excitation circuit. An excitation clock dc is input from a control circuit 9 described later, and the waveform is shaped, amplified, and output as an excitation signal ds.

Reference numeral 7 denotes an amplification detection circuit that amplifies and detects the induction signal is induced to the sense line group 3 and outputs an amplitude signal as of the induction signal. This circuit is used for calculating coordinate values. Reference numeral 8 denotes a phase detection circuit that detects the phase signal ps of the induction signal is.
FIG. 3 shows a detailed configuration diagram.

81 is an enhancement circuit, and 82 is a comparator. Amplifier circuit 81
Is supplied with an induction signal is from the sense scanning circuit 5.
The output of the comparator 82 is connected to one input of the exclusive OR circuit 83. The input to the other end of the exclusive OR circuit 83 is
The excitation clock dc is input, and the output is connected to an integration circuit 84 composed of a resistor and a capacitor. In this circuit, the excitation clock dc is used as the reference phase signal, and the induction signal is
Is detected as a voltage signal charged to the integration circuit 84.

The configuration of the phase detection circuit 8 shown in this embodiment is a circuit for detecting the difference between the phases of the induction signal is with respect to the excitation clock dc, and cannot detect the advance or delay. However, as a design matter, it is also conceivable that the induced signal advances compared to the reference signal and exhibits a delay behavior due to the way of taking the reference signal for phase detection, phase inversion by a circuit, delay, and the like. In such a case, a circuit for detecting the advance or delay of the phase may be provided. This circuit can be easily realized.

The configuration of the phase detection circuit is not essential for the present invention, and the point is that any circuit may be used as long as it detects the phase difference between two signals, and is not limited to this circuit. Returning to FIG. 1, the description will be continued. Control circuit 9
Controls each part, inputs each signal and calculates,
Find coordinate value and height information. The excitation scanning circuit 4 has a drive address dadr indicating the excitation line to be selected.
s, and the sense scanning circuit 5 is provided with a sense address sadrs indicating a sense line to be selected. Also, an amplitude signal as is input to calculate a coordinate value, and a phase signal ps is input to calculate height information. The control circuit 9 is realized by a microprocessor, and each arithmetic processing is performed by a program.

The coordinate indicator 10 is configured by a resonance circuit including a coil 11 and a capacitor 12. The resonance frequency of this resonance circuit is set around the frequency of the excitation clock dc. It is not always necessary to match.

(Regarding the Scanning and Coordinate Calculation Operations of the Coordinate Reading Device) Next, the operations will be described. First, the operation of selecting the excitation line group 2 and the sense line group 3 and the coordinate calculation operation will be described.

The control circuit 9 outputs the drive address dadrs and selects one of the excitation lines. As a result, the output of the excitation circuit 6 is connected to the selected excitation line, and the excitation line generates an AC magnetic field. The control circuit 9 outputs the sense address sadrs and selects the sense line group 3 sequentially while selecting one excitation line. The selected sense line is connected to the amplification detection circuit 7 and the phase detection circuit 8. The control circuit 9 repeats this operation.
This operation is called “scan”.

When the coordinate indicator 10 is not on the sense line plate 1, no signal is guided to the selected excitation line because the excitation line group 2 and the sense line group 3 are orthogonal to each other. However, when the coordinate indicator 10 is placed on the sense line board 1, an induction signal is generated in each sense line of the sense line group 3 according to the positional relationship between the sense line board 1 and the coordinate indicator 10. You. This is due to the effect of electromagnetic coupling between the excitation line, the coil 11, and the sense line.

FIG. 4 shows the guide signal is as a timing chart of scanning. FIG. 1 shows an example in which the excitation line group 2 is scanned from the top to the bottom of the figure, and the sense line group 3 is scanned from the left to the right in the figure. The position p of the coil 11 is in an area where the excitation line d2 and the sense line s2 intersect.

Now, in the case where the excitation line d0 and the sense line s0 are selected, that is, the region where both intersect is the coil
When the position is far from the position p of No. 11, the induced signal is not observed. As the area where the excitation line and the sense line intersect approaches the position p of the coil, the induction signal is increases, and becomes maximum when the excitation line d2 and the sense line s2 are selected. The induction signal is has a distribution as shown in the timing chart of FIG.

The induction signal is converted into an amplitude signal as by the amplification detection circuit 7, and the magnitude is read by the control circuit 9. Since the method of calculating the coordinates is not the gist of the present invention, the details are omitted, but the control circuit 9 uses the amplitude signals of the signals isp, isxl, isxh, isyl, isyh as shown in the timing chart of FIG. Calculate the coordinate value of the position where is placed.

(Regarding Operation for Calculating Height Information) Next, an operation for calculating height information will be described. It is known that the inductance changes when a metal approaches the coil. In the present coordinate reading device, a metal plate 13 is placed below the sense line plate 1. For this reason, the coordinate indicator 10
Rises and falls on the sense line plate 1, the inductance of the coil 11 changes. It is the gist of the present invention to capture this change in inductance and convert it into height information.

The control circuit 9 scans the sense line plate 1 as described above. During that time, the induction signal is is input to the phase detection circuit 8 and converted into the phase signal ps. The operation of the phase detection circuit 8 will be described with reference to the timing chart of FIG. In the figure, dc
Is an excitation clock, ds is an excitation signal, and is is an induction signal.
When the coordinate indicator 10 is placed immediately above the sense line plate 1, that is, when the height is 0, the induction signal is
It is induced with a constant phase difference with respect to ds.

A process in which the guidance signal is is processed will be described. First, the induction signal is amplified by an amplifier circuit 81 in the phase detection circuit 8, and further converted into a square wave by a comparator 82.
It becomes an induced signal shaped wave ip. The induction signal shaped wave ip and the excitation clock dc are phase-detected by the exclusive OR circuit 83 to become a detection signal pp. Further, the detection signal pp is converted into a DC signal by the integration circuit 84 and becomes a phase signal ps.

The inductance of the coil decreases as it approaches the metal plate. Therefore, on the contrary, as the coordinate indicator 10 moves away from the sense line plate 1, the inductance of the coil 11 increases, and as a result, the resonance frequency of the resonance circuit decreases. This effect affects the direction in which the phase of the induction signal is delayed. In FIG. 5, the induction signal ish is
This is a case where the marker pointer 10 is separated from the sense line plate 1, and shows that the coordinate pointer 10 is behind the guidance signal is when the coordinate pointer 10 is placed right above the sense line plate 1. This signal is also converted into a phase signal by the phase detection circuit 8.
Converted to psh. As is clear from the operation of the circuit, the magnitude of the phase signal psh is larger than the phase signal ps, and it can be seen that a change in phase can be detected. The control circuit 9 performs A / D conversion of the phase signal ps in the course of the scanning process, and takes in the magnitude. Then, the phase signal ps at the time when the signal isp used for calculating the coordinates shown in FIG. 4 is generated is adopted as the phase information for calculating the height information.

The timing of using the phase signal ps is not limited to the case where the signal isp is generated, and the phase can be detected if the induced signal is generated. Therefore, sampling may be performed at a specific timing. However, considering S / N,
It is preferable to detect the phase of isp, which is the largest induction signal. FIG. 6 shows the tendency of the phase signal ps with respect to the height. As shown in the figure, the curve is not a straight line, and the phase signal ps does not become height information as it is. By inputting the phase signal ps, the control circuit 9 converts this into height information. Although details are omitted, the tendency of height-phase shown in FIG. 6 is stored in the form of a conversion table, and it is easy to input the phase signal ps and look up the conversion table to determine the height. be able to.

(Configuration of Coordinate Reading Apparatus According to Second Embodiment) The gist of the present invention is that the inductance of the coil changes according to the distance from the metal plate placed below the sense line plate, and this changes with the excitation line, the coil, and the sense line 3. It is to obtain height information by detecting a change in the phase of an induction signal generated by electromagnetic coupling between persons. Therefore, the arrangement of the excitation line and the sense line is not limited to the first embodiment. FIG. 7 is a configuration diagram of the second embodiment. As shown in the figure, in the case of this embodiment,
The excitation line group 22 is arranged in the same direction as the sense line group 3 without being orthogonal. In addition, the two are partially overlapped. Other concepts are the same as in the first embodiment.

With the sense line plate 21 configured in this manner, the excitation circuit 4
To select one excitation line and give an excitation signal,
At the same time, when one sense line overlapping this excitation line is selected, an induction signal is generated in this sense line by electromagnetic coupling with the excitation line. The difference from the first embodiment is that a guidance signal is generated even when the coordinate indicator 10 is not on the sense line board 21. However, when the coordinate indicator 10 is placed on the sense line board 21, the coupling becomes stronger and a large guiding signal is generated. Therefore, the coordinate value can be obtained by observing the amplitude of the induction signal, and the phase signal for calculating the height information can also be detected. Since the induction signal is the sum of the signal coupled via the coil and the signal coupled directly to the excitation line, the phase signal is a reference compared to the first embodiment, that is, the value at the height 0 is different. . However, while the phase of the signal directly coupled to the excitation line is constant, the phase of the signal coupled via the coil is still affected by the distance from the metal plate disposed below the sense line plate. The height information can be calculated from the phase signal in the same manner as in the first embodiment. In the above embodiment, since the AC magnetic field is always generated from the excitation line,
A change in the resonance frequency of the resonance circuit of the coordinate indicator appears as a phase shift of the induction signal. Therefore, the height information of the coordinate indicator can be calculated by detecting the phase of the guidance signal as described above.

In a coordinate reading device of another system, that is, a system that alternately generates an AC magnetic field and receives an induction signal, the reception of the induction signal is not affected by the AC magnetic field.
The change in the resonance frequency appears as a frequency shift of the induction signal. Therefore, in the case of this method, it is apparent that the state of the switch can be determined by detecting the frequency of the induction signal instead of detecting the phase of the induction signal.

In any case, the height information of the coordinate indicator is detected by the frequency information, and a specific configuration for detecting the frequency information may be selected according to the configuration of the coordinate reading device to be applied. It is.

[Effects of the Invention] As described above, in the present invention, a metal plate is provided below a sense line plate on which an excitation line for generating an AC magnetic field and a sense line for inducing an induction signal are arranged. By providing a coordinate indicator to be coupled and configuring the wireless coordinate reader, the position of the coordinate indicator is determined from the frequency information of the induction signal by electromagnetic coupling between the excitation line, the coordinate indicator, and the sense line. Seeking height. Therefore, since the amplitude information of the guidance signal is not used, a wireless coordinate reading device that can accurately obtain height information without being affected by the position can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a wireless coordinate reading apparatus according to the present invention, FIG. 2 is a sectional view of a sense line plate, FIG. 3 is a block diagram of a phase detection circuit, and FIG. FIG. 5 is a timing chart of the phase detection operation,
FIG. 6 is a graph showing a change in the phase signal with respect to the height, FIG. 7 is a configuration diagram of the second embodiment, FIG. 8 is an explanatory diagram of a conventional height detection technique, and FIG. FIG. DESCRIPTION OF SYMBOLS 1 ... Sense line board 2 ... Excitation line group 3 ... Sense line group 4 ... Excitation scanning circuit 5 ... Sense scanning circuit 6 ... Excitation circuit 7 ... Amplification detection circuit 8 ... Phase detection circuit 9 ... Control circuit 10 Coordinate indicator 11 Coil 12 Capacitor

Claims (4)

(57) [Claims] A sense line plate on which an excitation line for generating an AC magnetic field based on the excitation signal and a sense line for inducing an induction signal are arranged; and a coordinate indicator electromagnetically coupled to the sense line plate. In a wireless coordinate reading device that obtains a coordinate value of a position where the coordinate indicator is placed based on a guidance signal, a metal plate is provided below the sense line plate, and based on frequency information of the guidance signal, the coordinate indicator is A wireless coordinate reader for detecting height information, comprising height information detecting means for obtaining height information of a position placed on a sense line plate. 2. The apparatus according to claim 1, wherein the height information detecting means receives the excitation signal and the induction signal, detects a phase of the induction signal, and outputs the phase signal as a phase signal. 2. The wireless coordinate reading device for detecting height information according to claim 1, further comprising a control device for converting a coordinate indicator into height information of a position placed on the sense line plate. 3. The wireless coordinate reader according to claim 1, wherein the coordinate indicator has a resonance circuit including a coil and a capacitor. 4. A sense line plate having a plurality of excitation line groups and a plurality of sense line groups arranged in an overlapping manner, and a coordinate indicator placed on the sense line plate and having a resonance circuit including a coil and a capacitor. A wireless coordinate reading device for sequentially applying an AC signal to the excitation line group, sequentially selecting the sense line group, and obtaining a coordinate value of a position where the coordinate indicator is placed from a guidance signal guided to the sense line; , A metal plate disposed below the sense line plate, an AC signal applied to the excitation line group, and an induction signal induced in the sense line are input, and the phase of the induction signal is detected to detect a phase signal. And a phase detection circuit that outputs the phase signal and converts the phase signal into height information of a position where the coordinate indicator is placed on the sense line plate. That the control device and the wireless coordinate reading device which detects the height information, characterized in that a.